Depositional System Evolution Characteristics in the Framework of Sequences of Silurian and Prediction of Favorable Zones in the Northern GuizhouSoutheastern Sichuan

Key words: 
• Northern GuizhouSoutheastern Sichuan

Abstract: Because of uplifting by Caledonian movement，most of the Silurian had been denuded and only its middle and lower series remained in the Northern GuizhouSoutheastern Sichuan. On the basis of the comprehensive study cores and log wells and outcrops, 8 sequences and 2 system tracts were divided by use of sequence stratigraphic method, there are two sequences (SSQ1~SSQ2)in Longmaxi Formation of the Lower Silurian，one sequence (SSQ3~SSQ4) in Xiaoheba Formation, four sequences(SSQ5~SSQ8) in middlelower Silurian Hanjiadian Formation. 3 depositional systems of delta, coastal and shelf were developed to explore the characteristics of the depositional systems and their planar distribution in isochronous stratigraphic framework. One is reef flat biolithite and granule limestone developed in the platform shallow facies and platform foreslope facies, mainly in highstand systematic tract of the third sequence SSQ3 and SSQ4 in the Shiniulan Age. The vertical distribution is in the middle and upper of the Shiniulan formation, and horizontal distribution in XuyongXishuiGuanyinqiao in the southern of the study area. The other is shallow continental shelf clasolite reservoir, mainly developed in highstand systems tract of the third sequence SSQ4 in the Xiaoheba Age, laterally distributed in NanchuanShizhuLichuan and other places.